In an elderly skilled‑nursing‑facility resident with multiple falls, not on anticoagulation, who recently recovered from COVID‑19 after dexamethasone therapy and now has thrombocytosis, what is the most likely etiology and appropriate management?

Thrombocytosis Post-COVID-19 in SNF Resident: Etiology and Management

Most Likely Etiology

The thrombocytosis is most likely a reactive phenomenon secondary to the inflammatory response from COVID-19 infection, potentially exacerbated by dexamethasone therapy. 1

Pathophysiologic Mechanisms

• COVID-19-induced inflammation triggers reactive thrombocytosis through cytokine-mediated stimulation of megakaryopoiesis, with platelet counts potentially exceeding 1000 × 10⁹/L as disease severity worsens 1
• Dexamethasone effects include complex interactions with coagulation cascades—while initially suppressing procoagulant factors during treatment, there is risk for rebound cytokine production after completion that can trigger further platelet elevation 2
• Extramedullary megakaryocytes in vascular beds represent a unique COVID-19 feature that contributes to both thrombocytosis and increased thrombotic risk 3

Key Differential Considerations

The combination of recent COVID-19, corticosteroid therapy, and progressive thrombocytosis creates a prothrombotic state distinct from primary hematologic disorders. This is reactive, not clonal thrombocytosis 1.

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Critical Management Priorities

Immediate Assessment

Monitor for thromboembolic complications aggressively, as this patient faces compounded thrombotic risk from COVID-19 recovery, elevated platelets, fall history, and SNF residence. 2, 4

• D-dimer levels should be checked immediately and serially monitored, as markedly elevated values predict thrombotic events even after clinical recovery 2, 4
• Clinical surveillance for deep vein thrombosis, pulmonary embolism, acute coronary syndrome, or stroke symptoms is essential, particularly within the first week post-dexamethasone completion 2, 4
• Contrast-enhanced CT should have a low threshold for use if any concerning symptoms develop, as clinical deterioration may be masked by residual corticosteroid effects 2

Thromboprophylaxis Strategy

Prophylactic-intensity anticoagulation should be strongly considered despite the patient not being hospitalized, given the high-risk profile. 3, 4

• The American Society of Hematology guidelines suggest against routine post-discharge anticoagulation for COVID-19 patients without VTE 3, but this recommendation applies to average-risk patients
• This patient's risk factors warrant exception: elderly SNF resident, multiple falls (high bleeding risk), recent severe COVID-19 requiring dexamethasone, and extreme thrombocytosis 4
• Extended anticoagulation with prophylactic-dose LMWH may be considered for high-risk patients in the immediate post-recovery period, particularly those with persistently elevated D-dimer 4

Critical Pitfall to Avoid

Do not assume clinical stability based on COVID-19 recovery alone. The period immediately following dexamethasone completion (days 1-7) represents a vulnerable window where rebound inflammation and thrombotic events cluster 2, 4. The mean time to thromboembolic complications post-recovery is 4.2 days 4.

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Anticoagulation Decision Algorithm

Risk Stratification

1. Check D-dimer level immediately 2, 4

   • If markedly elevated (>2-3× upper limit normal): Strong indication for prophylactic anticoagulation
   • If normal or mildly elevated: Close monitoring with repeat testing in 3-5 days

2. Assess bleeding risk from fall history 3

   • Recent falls (within 3 months): Higher bleeding risk
   • Remote fall history with stable mobility: Lower bleeding risk
   • Current mobility status and fall prevention measures in SNF

3. Individualized decision framework:

   • High thrombotic risk + acceptable bleeding risk: Initiate prophylactic-dose LMWH for 2-4 weeks with weekly D-dimer monitoring 4
   • High thrombotic risk + high bleeding risk: Intensive clinical surveillance without anticoagulation, with immediate imaging for any symptoms
   • Moderate risk profile: Serial D-dimer monitoring every 3-5 days for 2 weeks

Specific Anticoagulation Recommendations

If anticoagulation is initiated, use prophylactic-dose LMWH rather than therapeutic dosing. 3

• LMWH is preferred over unfractionated heparin for ease of administration in SNF setting 3
• Prophylactic dosing (e.g., enoxaparin 40 mg subcutaneous daily) balances thrombotic protection against fall-related bleeding risk 3
• Avoid therapeutic-intensity anticoagulation unless confirmed VTE is diagnosed, as bleeding risk outweighs benefit in this fall-prone patient 3

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Monitoring Protocol

Laboratory Surveillance

• Platelet count: Recheck in 1 week to assess trajectory (expect gradual decline as inflammation resolves) 1
• D-dimer: Weekly for 2-3 weeks or until normalized 4
• Renal function: Before initiating LMWH and weekly if anticoagulation started 5

Clinical Monitoring

• Daily assessment by SNF nursing staff for leg swelling, chest pain, dyspnea, neurologic changes, or new bleeding 5, 4
• Fall prevention measures must be optimized if anticoagulation is initiated 3

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Duration of Heightened Vigilance

The highest-risk period extends 1-2 weeks post-dexamethasone completion, with most thromboembolic events occurring within 7 days of clinical recovery 2, 4. Continue intensive monitoring through this window, then transition to standard SNF care if patient remains stable with normalizing inflammatory markers.